In operating a manual transmission, an equipment operator physically manipulates a gear shift lever in conjunction with the operation of a clutch. The gear shift lever is manually moved within a shift pattern. Typically, this movement takes place in a two dimensional plane. In other words, the equipment operator imparts both lateral and longitudinal movement to the shift lever. This movement causes the selection of discrete forward and reverse gears. The lateral and longitudinal movements are transmitted through a shift linkage and imparted to various shift rods within the transmission. Gears are selected when the shift lever reaches corresponding discrete positions in the shift pattern.
The conventional technique of manually imparting lateral and longitudinal movements through a shift linkage works acceptably well for many applications. However, this manual selection process is simply inadequate for other applications. Specifically, in competitive events gear shifting efficiency can be critically important. Missed shifts, in which a transmission is accidently placed in an unintended gear or neutral, degrade shifting efficiency. A single missed shift can cost precious fractions of a second and lead to a lost race.
In particular, missed shifts are a serious problem in connection with a rear-engine or mid-engine vehicle, in which a transmission is located toward the rear of the vehicle. In these configurations, the manual shift linkage which couples the shift lever to the transmission's shift rods can be a relatively large and complicated structure. This type of shift linkage imposes a certain amount of "slop" in transmitting movements at the shift lever to movements of shift rods. Moreover, this type of shift linkage fails to provide the type of accurate feedback that would inform the driver that a desired gear has been selected. Consequently, shifts are missed regularly.
This problem is further exaggerated when such vehicles are used in off-road competitions and for other recreational purposes. In off-road situations a driver experiences a considerable amount of bumping and jostling. Furthermore, this bumping and jostling often occurs while shifting and causes the driver to apply unintended movements to the shift lever. Accordingly, the driver's ability to quickly and accurately position a transmission's shift rods through a shift lever and a massive shift linkage are seriously degraded.